liver; N, node; S, stomach B: Celiac axis neuroblastoma Enhanced CT section of the abdomen at level of the kidney shows a large lobulated mass with irregular margins and calcification displacing the right kidney inferoposterior and laterally Note encased inferior vena cava (IVC) and aorta The IVC is displaced laterally and ventrally and to the right the superior mesenteric artery and celiac axis are completely surrounded by the mass A, Aorta; I, IVC; K, kidney; L, liver; S, spleen; white arrows, mass Wilms Tumor Wilms tumor is the most common intrarenal tumor seen in children The tumor can be massive before its discovery Wilms tumor should be considered in any child who has unexplained hematuria A solid renal mass demonstrated by US in infants and children is usually a Wilms tumor Because of the high frequency of tumor extension into the renal veins and inferior vena cava, these vascular structures should be examined by US Because Wilms tumors are usually large and expansive, the inferior vena cava often is extrinsically displaced by the tumor mass CT with bolus contrast enhancement may be required for confirmation of equivocal invasion in a patient suspected of having Wilms tumor CT scan can define the presence of an intrarenal mass and extent of tumor, visualizes vascular structures, identifies nodal involvement, defines internal hemorrhage and necrosis, evaluates the presence or absence of liver metastases, and provides some measure of renal excretory function Also, CT can determine whether a tumor is initially nonresectable or bilateral ( Fig 116.24 ) Chest CT is also performed at the initial evaluation to identify pulmonary metastases